1. Field of the Invention
The invention concerns an engine which runs notably on compressed air or any other gas, and more particularly using a piston travel control device which stops the piston at top dead centre for a period of time together with a device for recovering ambient thermal energy which can operate in mono- or bi-energy mode.
2. Description of the Related Art
The author has registered numerous patents concerning drive systems along with their installations using compressed air for totally clean operation in urban and suburban locations:    WO 96/27737 WO 97/00655    WO 97/48884 WO 98/12062 WO 98/15440    WO 98/32963 WO 99/37885 WO 99/37885
For the implementation of these inventions, he has also described in his patent application WO 99/63206, to which reference should be made, an engine piston travel control device and process which enables the piston to be stopped at top dead centre, a process also described in his patent application WO 99/20881 to which reference should also be made and concerning the operation of these engines with mono-energy or bi-energy and two or three powering modes.
In his patent application WO 99/37885 to which reference should also be made, he proposes a solution which increases the amount of usable and available energy which can be used which uses the fact that, before being introduced into the combustion and/or expansion chamber of the engine, the compressed air coming from the storage reservoir either directly or via the heat exchanger(s) of the ambient thermal energy recovery device is channelled into a thermal heater where, by increasing its temperature, the pressure and/or volume is further increased before introduction into the combustion and/or expansion chamber of the engine thus further considerably increasing the performance which can be obtained by the said engine.
In spite of the use of fossil fuel, the use of a thermal heater has the advantage of enabling clean continuous combustion to be used which can be catalyzed or depolluted by any existing means in order to obtain minimal polluting emissions.
The author has registered a patent no. WO 03/036088 A1, to which reference should be made, concerning a motor compressor-motor generator unit with supplementary compressed air injection operating in mono- or multi-energy.
In these types of engine operating with compressed air and comprising a storage reservoir of compressed air, the compressed air held at high pressure in the reservoir but whose pressure reduces as the reservoir is emptied, must be lowered to a stable intermediate pressure known as the final usage pressure in a buffer capacity known as the work capacity before being used in the engine cylinder(s). The well-known conventional pressure reducing valves using diaphragms and springs have very low flow rates and their use for this application requires very heavy poorly-performing devices; furthermore, they are very susceptible to freezing due to the humidity of the air chilled during the pressure drop.
To resolve this problem, the author has also registered a patent WO 03/089764 A1, to which reference should also be made, concerning a variable flow reducing valve and distribution system for compressed air injection engines, comprising a high-pressure compressed air tank and a work capacity.
The author has also registered a patent application WO 02/070876 A1 concerning an expansion chamber with a variable volume comprising two separate tanks one of which is in communication with the compressed air inlet and the other joined to the cylinder, which may be connected together or isolated from one another such that during the exhaust cycle, it is possible to charge the first of the tanks with compressed air then establish the pressure in the second at the end of the exhaust cycle while the piston is at TDC and before restarting its travel, the two tanks remaining in communication and releasing pressure together to carry out the engine stroke and that at least one of the tanks is provided with a means of changing their volume to enable the resultant torque of the engine to be varied at equal pressure.
The filling up of the chamber is always detrimental to the general efficiency in the operation of these “pressure reduction” engines.